1. Field of the Invention
This invention relates to a method and apparatus for forming trim cover and more particularly to an improved method and apparatus for forming trim cover being one of elements constituting a seat which is used as furniture or an automobile seat.
2. Description of the Prior Art
In general, trim cover of this type is made by integrally uniting a sheet of covering material such as fabric, synthetic leather or the like, a sheet of backing material and wadding material such as urethane slab or the like sandwiched between the covering and backing sheet, in which assembly of the three elements hollows appreciated as ornamental patterns are formed for decorating purposes.
Referring now to FIGS. 1 and 2, two conventional methods of forming trim cover will be described in order to facilitate understanding of the present invention.
In FIG. 1 illustrating one conventional method of forming trim cover, a sheet 30 of covering material, wadding material 32 and a sheet 34 of backing material are assembled in superposed relation, at a surface of which assembly of the three elements 30, 32 and 34 hollow patterns P are formed by stitching or welding predetermined portions of the assembly. In this conventional method, when the stitching or welding operation is carried out, the covering sheet 30 will be pulled toward the stitched or welded portion of the assembly, so that the wadding material 32 is thrust downwardly so as to be bulged out together with the backing sheet 34. Therefore, with this conventional method, it is not possible to keep the degree of the ups and downs of the patterns formed on the surface of the assembly large and in addition, it is inevitable that the appearance of the formed hollow patterns P of the assembly will become indistinct.
FIG. 2 shows the other conventional method of forming trim cover which was thought out in order to overcome the disadvantages of the above-mentioned conventional method. In FIG. 2A, channels 36 of a substantially U-shape in vertical section are formed in wadding material 32, a channeled surface side of which wadding material 32 is then covered with a sheet 30 of covering material. At this time, portions 38 of the sheet 30 of covering material positionally corresponding to the channeled portions 36 of the wadding material 32 are received in the corresponding channels 36 of the wadding material 32 in a manner to cover the walls of the wadding material 32 forming the channels 36. This assembly of the covering sheet 30 and wadding material 32 is then secured to a sheet 34 of backing material by sewing or welding the channeled portions of the assembly and the backing sheet 34 together, as shown in FIG. 2B. Thus, a trim cover having concave patterns P at the surface thereof is produced. With this conventional method, when the wadding material 32 is covered with the covering sheet 30, this assembling operation requires making of tucks in the portions 38 of the covering sheet 30 positionally corresponding to the channeled portions of the wadding material 32 in order to align the positionally corresponding portions 38 of the covering sheet 30 with the channels 36 of the wadding material 32. This tucking will leave wrinkles and waviness on the covering sheet 30, resulting in detracting from the appearance of the finished product. In addition, such tucking operation will take a great deal of trouble.